I agree...and as we seem to have swerved a bit from the original path of this post with the original poster nowhere in sight(William Tell, where did you go?
), the list of available materials is only so long, yet the number of ways of making it work for our application is much larger....we are left to further discuss the material properties and it's limits.
Pavise and Tod have mentioned two very interesting things. I remember arguing with someone on the topic of "wasted material" and at the moment I was exploring lost foam casting process(shell casting) which involved fabrication of the model out of styrofoam that would be invested and cast without prior elimination of the foam model(given foam is burnt out by the hot metal during the cast >>>Link
I used the foam block from which I was about to cut out the riser model to illustrate how much material was going to waste if such a riser was to be milled from a solid block of aluminum...ouch.
Though casting IS in fact a very dangerous practice and I agree with Pavise on it being a somewhat complex controlled process, in my opinion it is about as complex and as dangerous as operating a forge...those of us who can do it, simply have yet another technology at their disposal...those who don't...well - they don't.
I don't encourage anyone nor am I trying to discourage those who wish to try it. I can only say what I tried and how it went and why. When first attempting the lost foam casting method, I wasn't very successful due to my inability to reach and maintain the 1600-1800F temperature required for successful elimination of styrofoam during such casting process and thus ending up with pores and voids in the finished casting...oh and it was all happening outside in the winter time too.
With some better equipment such high temperatures can be easily reached/maintained and a rather large melt can be ready in as little as 15 minutes.(More info in the Technology/Metalworking forum) Manufacturers/suppliers like Metal Supermarket even suggest that materials supplied in blocks can be melted down and cast into a variety of complex shapes etc. etc.
With casting as yet another option, it is still somewhat limited to a set of specific alloys that lend themselves to the process without runing into much trouble later...some of this information can be found in the Wikipedia under "Aluminum Alloys">>>Link
I wasn't successful in my beginnings, but there was an individual inspired by our arguments who decided "it was meant to be" and went through with casting a riser using the sand casting method. Here is his little "photobucket"
If not casting, then there is yet another example of what can suffice in a somewhat low to medium power crossbow...though "nuts and bolts" designs don't seem to be very popular due to people fearing that they might loosen from vibrations.
Yet it doesn't seem to bother Danny >>>here
, crazy looking thing, isn't it.